壳聚糖涂膜处理对沙糖桔采后生理及品质的影响

目的研究壳聚糖涂膜处理对沙糖桔(Shatang mandarin)采后生理及品质的影响。方法常温条件下(20±2)℃采用0.5%、1.0%和1.5%壳聚糖涂膜处理,每4 d取一次样品,分别对沙糖桔果实的腐烂率、呼吸强度、可滴定酸含量、可溶性固形物含量和维生素C含量进行测定。结果与对照组相比,不同质量分数的壳聚糖涂膜处理均能有效抑制沙糖桔果实腐烂率的上升,延缓呼吸强度、可滴定酸、可溶性固形物和维生素C含量的下降。其中,1.5%壳聚糖涂膜处理对维持沙糖桔果实采后生理及品质的效果更显著。结论常温条件下,1.5%壳聚糖涂膜处理适用于沙糖桔果实的贮藏保鲜。     

壳聚糖涂膜对沪产冬枣贮藏期品质的影响

采用壳聚糖溶液处理沪产冬枣,结合PE保鲜袋包装贮藏,研究壳聚糖涂膜处理对沪产冬枣贮藏品质的影响。结果表明,采用1.5%壳聚糖涂膜处理沪产冬枣,到贮藏末期80 d时,VC含量、叶绿素含量、还原糖含量、水分含量及果实硬度均明显高于对照,并可有效抑制枣果果肉褐变的发生,降低烂果率,延缓冬枣果实的衰老。     

不同分子量壳聚糖涂膜贮藏鲫鱼的研究

将不同分子量(M1=1.6×106和M2=3.3×105,脱乙酰度为83.9%)的壳聚糖溶液涂膜于鲫鱼体表,观察壳聚糖对食品的保鲜作用。结果表明,涂膜能明显抑制需氧细菌、厌氧菌的繁殖,延缓挥发性盐基氮的增加。在4℃贮藏条件下,鲫鱼的一级鲜度保藏期较对照组可延长1～2d,二级鲜度延长3d左右,并且分子量较大的壳聚糖的抑菌效果比分子量较小的壳聚糖的抑菌效果好。      

不同分子量壳聚糖涂膜贮藏鲫鱼的研究

将不同分子量(M1=1.6×106和M2=3.3×105,脱乙酰度为83.9%)的壳聚糖溶液涂膜于鲫鱼体表,观察壳聚糖对食品的保鲜作用。结果表明,涂膜能明显抑制需氧细菌、厌氧菌的繁殖,延缓挥发性盐基氮的增加。在4℃贮藏条件下,鲫鱼的一级鲜度保藏期较对照组可延长1～2d,二级鲜度延长3d左右,并且分子量较大的壳聚糖的抑菌效果比分子量较小的壳聚糖的抑菌效果好。     

壳聚糖复合涂膜对鲜切冬枣安全性与贮藏品质的影响

以残次冬枣为实验材料,通过正交试验,以VC 的损失为指标确定了一种新型壳聚糖复合涂膜剂。结果表明：复合涂膜剂的最佳配方为1.0% 壳聚糖+1% 柠檬酸+2% 乳清蛋白+0.3% CaCl2。经该复合涂膜剂处理后的冬枣,在2℃下的贮藏品质明显提高。结果显示涂膜处理显著抑制了贮藏中微生物(细菌、霉菌及酵母、大肠杆菌)数量的上升(p ＜ 0.05),从而在一定程度上防止了微生物腐败的发生;降低了冬枣中营养物质的降解和转化,总糖及可溶性蛋白含量均被显著降低。此外抗氧化酶(CAT、POD、SOD)活性的检测结果也在一定程度上证明了复合涂膜处理对于冬枣品质的保护作用。     

壳聚糖涂膜对韭薹采后生理和品质的影响

运用壳聚糖作为涂膜剂处理韭薹,在4℃条件下储藏保鲜30d。储藏期间对韭薹的失重率、腐烂率、花苞开放率、花苞增重率、纤维素和VC含量进行了测定。实验结果表明:壳聚糖涂膜对韭薹有明显的保鲜效果,其中1%～1.5%壳聚糖涂膜有较好的保鲜效果,能够明显抑制韭薹腐烂和纤维素含量的增加和保持较高的VC含量。     

不同分子量壳聚糖涂膜对采后西番莲果实贮藏品质的影响

为研究不同分子量壳聚糖涂膜对采后西番莲的保鲜效果,本文以“钦蜜9号”西番莲果实为试材,分别采用30、50、100、150和200 kDa分子量的壳聚糖（1.5%,w/v）进行涂膜,以明确不同分子量壳聚糖涂膜对西番莲果实品质的影响。结果表明,不同分子量壳聚糖涂膜均能延缓西番莲果实的皱缩和果皮转黄,降低果实的失重率和抑制果实腐烂。其中,分子量越大的壳聚糖越有利于减轻西番莲果实成熟衰老、皱缩和腐烂,200 kDa涂膜果实的失重率在贮藏末期较同期30 kDa涂膜果实低近10%,并且150和200 kDa涂膜的果实在贮藏末期均未发生腐烂;较低分子量（30和50 kDa）和较高分子量（150 kDa）的壳聚糖涂膜则更有助于减缓果实贮藏期间失重、可溶性固形物和可溶性糖代谢以及维持果实可滴定酸、类黄酮和总酚含量,而150 kDa的壳聚糖涂膜在保持维生素C含量方面效果最好,在贮藏末期其含量是同期对照组的1.12倍。综上所述,不同分子量壳聚糖涂膜均有助于延缓西番莲果实衰老,减缓果实失水皱缩,保持果实品质,但具体效果在不同分子量间差别较大,综合而言,150 kDa壳聚糖更适合保持西番莲果实品质。     

壳聚糖涂膜对甜玉米品质和生理活性的影响

测定了壳聚糖涂膜对0℃和10℃温度下贮藏的甜玉米（Zea mays saccharata cv.sh2)呼吸强度、乙烯产量和品质指标的影响。壳聚糖涂膜能明显降低甜玉米的呼吸强度和乙烯产量,1．0％壳聚糖的效果明显优于0．5％壳聚糖。与对照相比,壳聚糖涂膜的甜玉米含较多的还原糖、可溶性总糖和蛋白质,而淀粉含量较低。壳聚糖涂膜并不引起乙醇的明显积累,也没有显著影响甲硫醚（DMS）的挥发量。在0℃的低温条件下,壳聚糖具有显著的抗菌作用,尤其是1．0％的浓度更为明显。壳聚糖涂膜减缓甜玉米品质劣变的作用与其抑制呼吸作用和乙烯合成有关。     

壳聚糖涂膜对鲜切苹果品质的影响

以山东红富士苹果为原材料,研究了不同浓度复合的壳聚糖、抗坏血酸及柠檬酸对鲜切苹果的外观和内部品质的影响。采用L9(34)正交实验设计,测定了贮藏过程中各组鲜切苹果的腐烂率、色泽、pH、可滴定酸、还原性糖等指标的变化情况。根据模糊权重法对贮藏4d的鲜切苹果外观和内部品质进行了综合评定。结果表明:选用2.0%柠檬酸、1.0%壳聚糖配制涂膜液和0.5%抗坏血酸溶液作为护色液,对鲜切苹果具有良好的保鲜效果。      

壳聚糖涂膜对鲜切苹果品质的影响

以山东红富士苹果为原材料,研究了不同浓度复合的壳聚糖、抗坏血酸及柠檬酸对鲜切苹果的外观和内部品质的影响。采用L9(34)正交实验设计,测定了贮藏过程中各组鲜切苹果的腐烂率、色泽、pH、可滴定酸、还原性糖等指标的变化情况。根据模糊权重法对贮藏4d的鲜切苹果外观和内部品质进行了综合评定。结果表明:选用2.0%柠檬酸、1.0%壳聚糖配制涂膜液和0.5%抗坏血酸溶液作为护色液,对鲜切苹果具有良好的保鲜效果。     

EFFECTS OF CHITOSAN ON GELLING PROPERTIES OF LOW QUALITY SURIMI

In order to produce a strong and elastic gel from low quality walleye pollock surimi, use of chitosan was examined. The strength of gels was nearly doubled by the addition of 1.5% chitosan when salted surimi pastes were set below 25C. In contrast, chitin did not cause any changes in the physical texture of gels. When salted surimi pastes containing 1.5% chitosan were set at 20C, a large decrease in the proportion of myosin heavy chain was observed with a concomitant increase in components with molecular weights heavier than myosin heavy chain. Since the addition of EGTA, an inhibitor of transglutaminase, to surimi reduced gel strength and minimized myosin heavy chain polymerization, it is suggested that the enhancing effect ofchitosan on the gel formation of walleye pollock surimi could be due to the activity of the endogenous transglutaminase known to be present in this surimi.     

EFFECT OF CHITOSAN COATING ON SHELF LIFE AND QUALITY OF FRESH-CUT MUSHROOM

ABSTRACT

The effect of chitosan coating in fresh‐cut mushroom preservation, including microbiological, enzyme activities, color characteristics and chemical quality attributes, was examined. However, application of chitosan coating to enzyme activity control and quality maintenance of fresh‐cut mushroom was investigated. Fresh‐cut mushrooms were treated with aqueous solution of 0.5, 1 and 2 g chitosan/100 mL, placed in polyethylene bags, and then stored at 4C. Application of chitosan coating delayed discoloration associated with reduced enzyme activities of polyphenoloxidase, peroxidase, catalase, phenylalanine ammonia lyase and laccase, as well as lower total phenolic content. Also, it reduced enzyme activities of cellulase, total amylase and α‐amylase. Microbiological development of the fresh‐cut mushroom treated with chitosan coating was also inhibited compared to the control. The results showed that increasing the concentration of chitosan coating enhanced the beneficial effects of chitosan on extended shelf life and maintained quality of fresh‐cut mushroom.

PRACTICAL APPLICATIONS

In general, the results showed that the application of chitosan coating (with optimum concentration of 2%) of oyster mushroom was observed to greatly inhibit the enzyme activities and lowest microbial count (Y, M and B) during storage at 4C for 15 days. Recommendations for selection of an appropriate chitosan concentration with refrigeration at 4C were given to be a potentially useful tool for extending the shelf life of fresh oyster mushroom. Furthermore, from a technological point of view, it would be conceivable to use chitosan coating in processed mushrooms provided that their safety is assessed and their commercial feasibility is demonstrated. It is concluded that the technique used produced good results; the product showed good quality during processing and storage with respect to microbiological, physical and chemical properties. Also, this technique is important to prevent the decrease in market value and the concomitant economic losses.

     

机械损伤对富士苹果采后软化生理的影响

以富士苹果为试材,研究了机械损伤后在5℃和18℃贮藏条件下对果肉颜色、果肉硬度、可溶性果胶和原果胶含量、纤维素含量及纤维素酶活性的影响.结果表明,机械损伤导致果肉L*、果肉硬度、原果胶含量、纤维素酶活性均快速下降;a*值显著上升;b*值、纤维素含量、可溶性果胶含量呈前期上升后期下降的趋势:在贮藏过程中,伤害部位的生理生化指标均显示了上升和下降的反复趋势.说明机械损伤破坏了细胞壁的组织结构,促进了果实的快速软化;随着贮藏期的延长,愈伤组织逐渐形成,从而达到伤害部位的自我修复.而且受伤果实在低温下贮藏各种生理代谢缓慢,有效地延缓了受伤果的快速衰老.     

NO减压处理对富士苹果采后生理特性的影响

以"富士"苹果为试材,研究了常温贮藏条件下N0(一氧化氮)减压(0.5个大气压,50.662 5 kPa)处理对果实采后生理的影响.结果表明:NO减压处理可延缓果实可溶性固形物的降低;显著抑制果实乙烯释放量,显著降低呼吸强度;减缓果肉硬度下降;显著延缓丙二醛(MDA)含量的升高,从而降低膜脂过氧化程度;提高了POD的活性,减少H2O2的积累.结果表明:适宜浓度NO处理可明显改善其贮藏品质,延缓衰老.     

1-MCP处理对"美国8号"苹果采后生理的影响

以“美国8号”苹果为试材，研究了0℃贮藏条件下1-MCP（1-甲基环丙烯）处理对果实采后生理的影响。结果表明：1μL/L1-MCP处理可显著抑制贮藏期间果实乙烯释放量，延缓其跃变高峰的出现，推迟ACO（ACC氧化酶）活性高峰及呼吸跃变峰的出现，抑制采后初期ACO活性及呼吸速率的上升；减缓果肉硬度下降；同时降低脂氧合酶（LOX）活性，并延迟其峰值的出现，延缓了丙二醛（MDA）含量和相对膜透性的升高，从而降低膜脂过氧化程度。结果表明：1-MCP可显著改善其贮藏品质。     

CONTROLLED ATMOSPHERE STORAGE AND EDIBLE COATING EFFECTS ON STORAGE LIFE AND QUALITY OF TOMATOES

Tomatoes at pink stage maturities were coated with Semperfresh^TM edible fruit coating which is composed of sucrose esters of fatty acids, sodium carboxymethyl cellulose and mono-diglycerides of fatty acids. One group of coated and uncoated tomatoes were stored at 23 × 2C under air atmosphere, another group was stored at 12C under air atmosphere and third group was stored at 12C, 93–95% RH in a controlled atmosphere (CA) containing 3% CO₂, 3% O₂ and 94% N₂. Samples of tomatoes were analyzed for firmness, weight loss, titratable acidity, pH, soluble solids, sugars, ascorbic acid and lycopene to examine changes in quality during storage. Semperfresh^TM edible fruit coating was found to be significantly effective at both storage temperatures (23 × 2C and 12C) in air to delay changes in firmness, titratable acidity, pH, soluble solids, sugars, ascorbic acid and lycopene. Semperfresh^TM fruit coating reduced fruit weight loss as compared to fruit without coating but the difference between coated and uncoated tomatoes was not significant. Shelf-life of pink tomatoes was increased 3 days at 23 × 2C and 6 days at 12C in air by coating. CA storage delayed compositional changes in tomatoes significantly as compared to air storage of coated and uncoated tomatoes. CA storage also had a significant potential for reducing weight loss and microbial spoilage. Tomatoes were stored 40 days in CA. Coated and uncoated tomatoes exhibited the same results in CA.     

白灵菇采后低温气调包装保鲜试验

以6种特制的抑菌膜、2种普通PE保鲜膜为试验材料,研究在低温条件下不同特性保鲜膜对白灵菇的气调保鲜效果,确定最适白灵菇保鲜膜.结果表明,厚度为0.03mm的抑菌膜Ⅱ、Ⅲ包装白灵菇,在0℃下贮藏90d.